<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<div id="dv1"></div>
	</body>
	<script>
	// window.setInterval预设置，每隔多长时间执行一次
	window.setInterval(function(){
		var div=document.getElementById("dv1")
		console.log(div)
		div.innerHTML=new Date()
	},1000)
	
	
	</script>
</html>
